ObjectFactory2D
cern.colt.matrix.tobject

Class ObjectFactory2D

  • All Implemented Interfaces:
    Serializable, Cloneable


    public class ObjectFactory2Dextends PersistentObject
    Factory for convenient construction of 2-d matrices holding Object cells. Also provides convenient methods to compose (concatenate) and decompose (split) matrices from/to constituent blocks.

     

    Construction Use idioms like ObjectFactory2D.dense.make(4,4) to construct dense matrices, ObjectFactory2D.sparse.make(4,4) to construct sparse matrices.
    Construction with initial values Use other make methods to construct matrices with given initial values.
    Appending rows and columns Use methods appendColumns, appendRows and repeat to append rows and columns.
    General block matrices Use methods compose and decompose to work with general block matrices.
    Diagonal block matrices Use method composeDiagonal to work with diagonal block matrices.

     

    If the factory is used frequently it might be useful to streamline the notation. For example by aliasing:

      ObjectFactory2D F = ObjectFactory2D.dense;  F.make(4,4);  ... 
    See Also:
    Serialized Form
    • Field Detail

      • dense

        public static final ObjectFactory2D dense
        A factory producing dense matrices.
      • sparse

        public static final ObjectFactory2D sparse
        A factory producing sparse matrices.
    • Method Detail

      • appendColumns

        public ObjectMatrix2D appendColumns(ObjectMatrix2D A,                           ObjectMatrix2D B)
        C = A||B; Constructs a new matrix which is the column-wise concatenation of two other matrices.
                 0 1 2         3 4 5         appendColumns         6 7         8 9         -->         0 1 2 6 7          3 4 5 8 9  
      • appendRows

        public ObjectMatrix2D appendRows(ObjectMatrix2D A,                        ObjectMatrix2D B)
        C = A||B; Constructs a new matrix which is the row-wise concatenation of two other matrices.
                 0 1          2 3          4 5         appendRows         6 7         8 9         -->         0 1          2 3          4 5         6 7         8 9  
      • compose

        public ObjectMatrix2D compose(ObjectMatrix2D[][] parts)
        Constructs a block matrix made from the given parts. The inverse to method decompose(ObjectMatrix2D[][], ObjectMatrix2D).

        All matrices of a given column within parts must have the same number of columns. All matrices of a given row within parts must have the same number of rows. Otherwise an IllegalArgumentException is thrown. Note that nulls within parts[row,col] are an exception to this rule: they are ignored. Cells are copied. Example:

        Code Result
         ObjectMatrix2D[][] parts1 = { { null, make(2, 2, 1), null }, { make(4, 4, 2), null, make(4, 3, 3) },         { null, make(2, 2, 4), null } }; System.out.println(compose(parts1)); 
        8 x 9 matrix
        0 0 0 0 1 1 0 0 0
        0 0 0 0 1 1 0 0 0
        2 2 2 2 0 0 3 3 3
        2 2 2 2 0 0 3 3 3
        2 2 2 2 0 0 3 3 3
        2 2 2 2 0 0 3 3 3
        0 0 0 0 4 4 0 0 0
        0 0 0 0 4 4 0 0 0
         ObjectMatrix2D[][] parts3 = { { identity(3), null, }, { null, identity(3).viewColumnFlip() },         { identity(3).viewRowFlip(), null } }; System.out.println("\n" + make(parts3)); 
        9 x 6 matrix
        1 0 0 0 0 0
        0 1 0 0 0 0
        0 0 1 0 0 0
        0 0 0 0 0 1
        0 0 0 0 1 0
        0 0 0 1 0 0
        0 0 1 0 0 0
        0 1 0 0 0 0
        1 0 0 0 0 0
         ObjectMatrix2D A = ascending(2, 2); ObjectMatrix2D B = descending(2, 2); ObjectMatrix2D _ = null;  ObjectMatrix2D[][] parts4 = { { A, _, A, _ }, { _, A, _, B } }; System.out.println("\n" + make(parts4)); 
        4 x 8 matrix
        1 2 0 0 1 2 0 0
        3 4 0 0 3 4 0 0
        0 0 1 2 0 0 3 2
        0 0 3 4 0 0 1 0
         ObjectMatrix2D[][] parts2 = { { null, make(2, 2, 1), null }, { make(4, 4, 2), null, make(4, 3, 3) },         { null, make(2, 3, 4), null } }; System.out.println("\n" + Factory2D.make(parts2)); 
        IllegalArgumentException
        A[0,1].columns != A[2,1].columns
        (2 != 3)
        Throws:
        IllegalArgumentException - subject to the conditions outlined above.
      • composeDiagonal

        public ObjectMatrix2D composeDiagonal(ObjectMatrix2D A,                             ObjectMatrix2D B)
        Constructs a diagonal block matrix from the given parts (the direct sum of two matrices). That is the concatenation
                 A 0         0 B  
        (The direct sum has A.rows()+B.rows() rows and A.columns()+B.columns() columns). Cells are copied.
        Returns:
        a new matrix which is the direct sum.
      • decompose

        public void decompose(ObjectMatrix2D[][] parts,             ObjectMatrix2D matrix)
        Splits a block matrix into its constituent blocks; Copies blocks of a matrix into the given parts. The inverse to method compose(ObjectMatrix2D[][]).

        All matrices of a given column within parts must have the same number of columns. All matrices of a given row within parts must have the same number of rows. Otherwise an IllegalArgumentException is thrown. Note that nulls within parts[row,col] are an exception to this rule: they are ignored. Cells are copied. Example:

        Code matrix --> parts
                 ObjectMatrix2D matrix = ... ;         ObjectMatrix2D _ = null;         ObjectMatrix2D A,B,C,D;         A = make(2,2); B = make (4,4);         C = make(4,3); D = make (2,2);         ObjectMatrix2D[][] parts =          {            { _, A, _ },            { B, _, C },            { _, D, _ }         };         decompose(parts,matrix);         System.out.println("\nA = "+A);         System.out.println("\nB = "+B);         System.out.println("\nC = "+C);         System.out.println("\nD = "+D);  
        8 x 9 matrix
        9 9 9 9 1 1 9 9 9
        9 9 9 9 1 1 9 9 9
        2 2 2 2 9 9 3 3 3
        2 2 2 2 9 9 3 3 3
        2 2 2 2 9 9 3 3 3
        2 2 2 2 9 9 3 3 3
        9 9 9 9 4 4 9 9 9
        9 9 9 9 4 4 9 9 9

        A = 2 x 2 matrix
        1 1
        1 1

        B = 4 x 4 matrix
        2 2 2 2
        2 2 2 2
        2 2 2 2
        2 2 2 2

        C = 4 x 3 matrix
        3 3 3
        3 3 3
        3 3 3
        3 3 3

        D = 2 x 2 matrix
        4 4
        4 4

        Throws:
        IllegalArgumentException - subject to the conditions outlined above.
      • diagonal

        public ObjectMatrix2D diagonal(ObjectMatrix1D vector)
        Constructs a new diagonal matrix whose diagonal elements are the elements of vector. Cells values are copied. The new matrix is not a view. Example:
                 5 4 3 -->         5 0 0         0 4 0         0 0 3  
        Returns:
        a new matrix.
      • diagonal

        public ObjectMatrix1D diagonal(ObjectMatrix2D A)
        Constructs a new vector consisting of the diagonal elements of A . Cells values are copied. The new vector is not a view. Example:
                 5 0 0 9         0 4 0 9         0 0 3 9         --> 5 4 3  
        Parameters:
        A - the matrix, need not be square.
        Returns:
        a new vector.
      • make

        public ObjectMatrix2D make(Object[][] values)
        Constructs a matrix with the given cell values. values is required to have the form values[row][column] and have exactly the same number of columns in every row.

        The values are copied. So subsequent changes in values are not reflected in the matrix, and vice-versa.

        Parameters:
        values - The values to be filled into the new matrix.
        Throws:
        IllegalArgumentException - if for any 1 <= row < values.length: values[row].length != values[row-1].length .
      • make

        public ObjectMatrix2D make(Object[] values,                  int rows)
        Construct a matrix from a one-dimensional column-major packed array, ala Fortran. Has the form matrix.get(row,column) == values[row + column*rows]. The values are copied.
        Parameters:
        values - One-dimensional array of Objects, packed by columns (ala Fortran).
        rows - the number of rows.
        Throws:
        IllegalArgumentException - values.length must be a multiple of rows .
      • make

        public ObjectMatrix2D make(int rows,                  int columns)
        Constructs a matrix with the given shape, each cell initialized with zero.
      • make

        public ObjectMatrix2D make(int rows,                  int columns,                  Object initialValue)
        Constructs a matrix with the given shape, each cell initialized with the given value.
      • repeat

        public ObjectMatrix2D repeat(ObjectMatrix2D A,                    int rowRepeat,                    int columnRepeat)
        C = A||A||..||A; Constructs a new matrix which is duplicated both along the row and column dimension. Example:
                 0 1         2 3         repeat(2,3) -->         0 1 0 1 0 1         2 3 2 3 2 3         0 1 0 1 0 1         2 3 2 3 2 3  

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